1.Field of the Invention
This invention relates to an electric connector and more specifically to an improvement in an electric connector which has a rear holder to prevent terminals installed in terminal accommodating chambers in the housing from slipping off from the rear of the housing.
2. Description of the Prior Art
Between the terminal and the terminal accommodating chamber is usually provided a locking means called a terminal lance or case lance to prevent the terminal from slipping off from the rear of the housing. The terminal lance is a lance cut and raised from the terminal and adapted to engage with an engagement groove formed in the terminal accommodating chamber's inner wall. The case lance is a resilient engagement arm provided to the accommodating chamber's inner wall to engage with a shoulder or engagement hole in the terminal.
As the connector has an increasing number of terminals and the terminal size decreases, the raised lance and the resilient engagement arm also become smaller, making it difficult to provide a sufficient strength and retaining force. In recent years, a method has come into use which uses a combination of the above-mentioned engagement means and a rear holder, separate from the housing, to bolster the terminal retaining force and improve the reliability of the electric connection. FIGS. 8A and 8B show one example of a conventional electric connector having a rear holder (Japan Patent Publication No. Heisei 1-43986), with FIG. 8A illustrating the rear holder b provisionally engaged with the housing a and FIG. 8B showing it fully engaged.
In the provisional engagement condition of the electric connector of FIG. 8, the terminals c are inserted into terminal accommodating holes a.sub.1 until engagement pieces c.sub.1 engage with terminal engagement claws a2 to provide a preliminary locking between the terminals and the housing. Then the rear holder b is moved to a full engagement position to securely lock the terminals c by an edge portion b.sub.1 of the holder.